In recent years, the use of photocatalysts has been started in pieces of glass as members for buildings, outer walls/inner walls of buildings, side mirrors of automobiles, coatings for automobiles, sound-roof walls for highways, antibacterial towels, and air clearers from various viewpoints of staining, dust-proofing, decontamination, anti-bacteria, and others. In such markets, a drastic expansion thereof in the future is forecasted. In particular, members used outdoors out of members for buildings have a self-cleaning effect that contaminants adhering to the surface thereof are caused to flow out by ultraviolet rays and rain; thus, the expansion of the markets thereof is expected very much.
In antifouling films applied or attached to the surface of these members, for example, TiO2, ZnO, ZrO2 or SrTiO3 is used as a photocatalyst. The surface of the photocatalyst is activated when the surface is The surface of the photocatalyst is activated when the surface is subjected to the radiation of ultraviolet rays. The adhering contaminants are then decomposed. Furthermore, a self-cleaning effect that the contaminants (or decomposed products of the contaminants) are easily washed away by rain or the like can be obtained.
However, when the various members, wherein a photocatalyst is formed, are each stored, transported, worked or applied, the layer of the photocatalyst may be damaged. Once the layer is damaged, loss of time, processing, and costs is generated on the basis of the step of repairing the layer. Thus, works for the repair on the spot are very difficult. In recent years, therefore, a protecting material has been desired for protecting the photocatalytic layer in the step of forming the photocatalytic layer, and at the time of forwarding or storing the member.
Hitherto, a material for protecting a photocatalytic layer has been suggested as a trial for overcoming the above-mentioned problem. For example, disclosed is a protecting material for a photocatalyst wherein a polyepoxy compound is blended with an acryl-based polymer (see, for example, Patent Document 1). However, it has been proved that the application of the protecting material to these members, which are poor in weather resistance and are frequently stored and protected in particular outdoors is insufficient even in accordance with this suggestion.
Patent Document 1: JP-A-2003-82304